1. Field of the Invention
The present invention relates to an interconnection assembly for personal computer systems, and more particularly, to an interconnection assembly for a magnetic disk storage unit of the Winchester-type including a disk drive.
2. Description of the Prior Art
It is well known for personal computer systems to include both rigid disk magnetic storage units, as well as floppy disk magnetic storage units. More specifically, it is known for the rigid disk magnetic storage units to be of the Winchester-type wherein a rigid disk and an associated read/write magnetic transducer are permanently mounted within a sealable housing which, in turn, is mounted to a disk drive means. As compared to floppy disk units, the Winchester-type disk units are capable of storing substantially more information and operating at substantially increased speeds. For example, typical two-sided floppy disks currently used in personal computer systems can store about 360,000 bytes of data, whereas a typical hard disk unit may store about ten megabytes of data (one megabyte is approximately equal to one million bytes).
Conventional practice in the design and manufacture of many personal computer systems is to build a Winchester-type disk unit and disk drive into the computer's systems unit as an essentially permanent or "fixed" component. Such design is found, for example, in the IBM PC XT manufactured by IBM Company. In other words, the Winchester-type disk unit in such systems forms an intergal part of the systems unit and is not readily, or conveniently, removable by an ordinary user of the computer. By way of contrast, floppy disks are readily removable from the systems unit, although the drive and transducer units for the floppy disks are, of course, a permanent part of the systems unit.
It is also known to provide so-called "add-on" peripheral storage subsystem units for personal computers and the like. These add-on subsystem units are typically "stand-alone" devices which are connected, via data-transmitting cable, to the systems unit to provide additional memory capacity for the computing system. It is known that these add-on subsystem units can be designed to handle either floppy disks or hard disks of the Winchester-type built permanently into the unit.
The fixed nature of Winchester-type disk units in such conventional personal computer systems, whether as a part of a systems unit or an add-on subsystem, has several shortcomings. One shortcoming arises in situations where there is a periodic need to completely remove data from the Winchester-type disk system, say for security purposes. Such a security need may arise, for example, in military or government offices where material on a magnetic media may be of a classified nature such that it, or the media upon which it is stored, must be removed from a computer and stored in a secure location when not in use. In such instances, data on fixed Winchester-type disks in a computer system must be first transferred to a floppy disk or to a so-called "streaming tape" which can be removed from the system, then the Winchester-type disk must be erased. Such copying is expensive and time consuming. For example, about thirty minutes is required to copy the contents of a ten megabyte hard disk onto a conventional one-quarter inch streamer tape and, in addition, there is the cost of the mechanism for the streamer tape as well as the tape itself. Accordingly, streaming tapes are not considered to be practical by software engineers for providing "on-line" storage for personal computer systems. Likewise, the copying of information from a fixed disk system onto floppy disks is similarily time consuming, expensive and, in many instances, impractical.
Even when there is no security need to remove data from a Winchester-type fixed disk, it is often desirable to transfer data from the Winchester-type disk onto another storage media so as to provide a "back-up" or archival copy of the information for safe-keeping, or to provide additional "on line" storage. However, whether the need is to remove information for erasure or merely for copying, the process of removing data from Winchester-type disks in conventional personal computer systems is slow, inconvenient and expensive. Further, the shortcomings of presently available data transfer means are likely to become more acute as the storage capabilities increase for the Winchester-type hard disk units which are used in personal computer systems because, with more data stored on the hard disks, the transfer time to back-up streamer tapes or floppy disk systems is proportionately increased, as is the amount of streamer tape required or the number of floppy disks which must be used.